1. Field of the Invention
The present invention relates generally to printing presses and, more specifically, to adjustment systems and methods for printing press ink fountains.
2. Description of the Related Art
In an offset printing press, ink is contained in an assembly known as a fountain and picked up by a first roller that is partially immersed in the fountain. The first roller transfers the ink to a second roller with which it is in contact. A typical offset printing press ink fountain assembly also includes a mechanism to regulate with considerable precision the amount of ink the first roller picks up and its distribution along the roller. This mechanism typically comprises an ink blade that extends along the length of the first roller and a number of adjustment screws, also known as keys—often a dozen or more in a typical press—spaced along the length of the ink blade at intervals typically on the order of about an inch. Due to the paste-like viscosity of the ink, the blade is needed to press the ink into the roller and thereby ensure good adhesion and, moreover, an even distribution of ink. The adjustment screws control the extent to which the blade presses the ink into the roller. A distal end of each adjustment screw abuts the rear surface of the blade, and a proximal end has a knurled adjustment knob. The blade is somewhat flexible and resiliently biased toward the roller. By turning an adjustment screw, an operator can adjust the gap between the front surface of the blade and the surface of the roller. Turning an adjustment screw such that it extends toward the roller, the distal end pushes the blade against the bias to narrow the gap. Turning an adjustment screw such that it retracts away from the roller, the distal end moves with the blade in the direction the blade is biased to widen the gap. The wider the gap, the thicker the layer of ink that is deposited on the roller.
An operator typically adjusts the screws to suit each printing job. To set up the press, the operator may run some test prints and then adjust one or more of the screws if the prints do not have an even appearance. The operator may make many test prints, each time adjusting some of the screws, until satisfactory results are obtained. This trial-and-error process of adjusting the screws is time-consuming and inconvenient. The screws also can be notoriously difficult to turn, especially by an operator having ink-slicked hands, and the stubby cylindrical screw heads do not provide much leverage. Furthermore, if an operator adjusts the press to suit a first printing job, then makes some prints, and then wishes to run a second printing job, the operator must adjust the press to suit the second printing job. If the operator wishes to return to the first printing job and make some more prints, the operator needs to adjust the press yet again.
Mechanisms have been suggested in the art for facilitating re-adjustment of a printing press so as to note the screw settings for a particular printing job. For example, U.S. Pat. No. 3,623,430 to Lessun describes screws with numeric scales printed on them. After the screws have been adjusted to suit the printing job, the operator can note the settings on the scales. If a job is interrupted by the need to run another job, an operator can later return the press to the settings for the previous job by turning the screws until their scales read as they did previously. Nevertheless, there are deficiencies in this approach, including that the scales are difficult to read and keep clean, and that the system cannot readily be retrofitted to existing presses.
It would be desirable to provide a system for adjusting an offset printing press ink fountain that is easy to use and maintain and that can be retrofitted to existing presses. The present invention addresses these problems and deficiencies and others in the manner described below.